In this work, we designed a novel CuO/Al2CuO4 catalyst by a phase and interphase engineering approach, which enables the electrochemical conversion of carbon dioxide to ethylene with ultrahigh activity and selectivity.

A highly efficient and platinum group metal (PGM)‐free oxygen evolution reaction (OER) electrode is developed by immobilizing Ni3N particles on the electrochemically reconstructed amorphous oxy‐hydroxides surface, resulting in a twofold higher industrial relevance current density of 1 A cmgeo−2 at an ultra‐small overpotential η(O2) of 271 mV, with a high turnover frequency of 2.53 s−1, high Faradic efficiency of 99.6 % and exceptional OER stability of 1000 h in continuous electrolysis. Such a unique amorphous‐crystalline interface with enriched active sites greatly facilitates electron transport and OER kinetics at the electrode‐electrolyte interface. Further, combined with an efficient PGM‐free cathode (MoNi4/MoO2@Ni), this electrode demonstrates a current density of 685 mA cmgeo−2 at 1.85 Vcell at 70 °C in an anion exchange membrane water electrolyzer (AEMWE) operated with ultra‐pure water‐electrolyte. These findings highlight the design of highly‐efficient oxygen‐evolving catalysts and significant advancement in the practical implementation of AEMWEs for grid‐scale hydrogen production.

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Abundant availability of seawater grants economic and resource‐rich benefits to water electrolysis technology requiring high‐purity water if undesired reactions such as chlorine evolution reaction (CER) competitive to oxygen evolution reaction (OER) are suppressed. Inspired by a conceptual computational work suggesting that OER is kinetically improved via a double activation within 7 Å‐gap nanochannels, RuO2 catalysts are realized to have nanoscopic channels at 7, 11, and 14 Å gap in average (dgap), and preferential activity improvement of OER over CER in seawater by using nanochanneled RuO2 is demonstrated. When the channels are developed to have 7 Å gap, the OER current is maximized with the overpotential required for triggering OER minimized. The gap value guaranteeing the highest OER activity is identical to the value expected from the computational work. The improved OER activity significantly increases the selectivity of OER over CER in seawater since the double activation by the 7 Å‐nanoconfined environments to allow an OER intermediate (*OOH) to be doubly anchored to Ru and O active sites does not work on the CER intermediate (*Cl). Successful operation of direct seawater electrolysis with improved hydrogen production is demonstrated by employing the 7 Å‐nanochanneled RuO2 as the OER electrocatalyst.